4i,' OF THE WOOD. 



It has even been asserted that the date of peculiarly 

 severe winters 4nay be found in the harder more con- 

 densed rings formed at those periods ; and moreover, 

 that the north side of a tree may always be know by the 

 narrowness and density of the rings on that side. All 

 this is controverted by Mirbel, chiefly on th( authority 

 of Du Hamel, who nevertheless scarcely says enough 

 to invalidate the ancient opinion on the whole. It is 

 very true that there may be occasional interruptions in 

 the formation of the wood from cold or fickle seasons, 

 and that in some trees the thin intermediate layers, 

 hardly discernible in general, which unite to form the 

 principal or annual ones, may, from such fluctuation of 

 seasons, become more distinct than is natural to them. 

 Such intermediate layers are even found more numerous 

 in some trees of the same species and age than in 

 others. But as there is always a most material differ- 

 ence between summer and winter, so I belie\e will there 

 always be a clear distinction between the annual rings 

 of such trees as show them at all. Trees of hot coun- 

 tries indeed, as Mahogany, and evergreens in general, 

 have them but indistinctly marked ; yet even in these 

 they are to be seen. With regard to their greater com^ 

 pactness on the north side of a tree, Du Hamel justly 

 explodes this idea. In fact, there is most wood formed^, 

 and consequently these circles are broadest, on the side 

 most favorable to vegetation, and where there are most 

 branches and leaves. This in a solitary tree is generally 

 towards the south ; but ii is easy to perceive the occa- 

 sional variations which must ari^e from local exposure, 

 soil, moisture, and other causes. 



